Episode 512: Why Did the Apostles Keep the Old Testament Holy Days?

Which set of Holy Days were used and kept by Jesus and His apostles in the New Testament era? All religions use some kinds of Holidays or Holy Days. Did the Apostles of Jesus use the Holy Days that were clearly already established and listed in the Bible or use worldly days? Did they re-label pagan days such as Christmas and celebrate them for Christ? What about Easter and Halloween? Remember the author of the NT believed in the authenticity of the Old Testament.